apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF

echo "deb http://download.mono-project.com/repo/debian wheezy main" | tee /etc/apt/sources.list.d/mono-xamarin.list
echo "deb http://download.mono-project.com/repo/debian wheezy-apache24-compat main" | tee -a /etc/apt/sources.list.d/mono-xamarin.list
echo "deb http://download.mono-project.com/repo/debian wheezy-libjpeg62-compat main" | tee -a /etc/apt/sources.list.d/mono-xamarin.list

apt-get update
apt install mono-devel
#apt-get install mono-devel mono-complete referenceassemblies-pcl ca-certificates-mono